"People think the toilet seat is dirty," Dr Gerba, who is known as "Dr Germ", says.

"But there is about 200 times more faecal bacteria on a typical chopping board compared to the average toilet seat."

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Dr Charles Gerba ... he says there is about 200 times more faecal bacteria on a typical chopping board compared to the average toilet seat.

Bathrooms tend to be over-cleaned and sanitised. But the preparation of raw food products in the kitchen means it has become the perfect breeding ground for germs.

The cleanest looking surfaces can be the dirtiest.

"Wiping down a kitchen bench actually spreads the germs," says the professor from the University of Arizona, who is in Australia representing White King Bleach.

He implores people to disinfect key areas in the kitchen and regularly wash their hands because this can reduce the odds of getting an illness by 50 per cent.

The Salmonella bug in a petrie dish in a laboratory at Melbourne University.Credit:John Lamb

"My research shows 15 per cent of sponges and dish cloths have salmonella growing in [them]," he says. "We need to regularly throw them out and disinfect the key areas."

He suggests people carry anti-bacterial wipes and wash their hands regularly.

Chopping boards are a breeding ground for germs.Credit:Natalie Boog

Mary-Louise McLaws, professor of epidemiology in healthcare infection and infectious diseases control at the University of New South Wales, agrees that sponges should be thrown out each week.

But she disagrees with the suggestion by Dr Gerba that we need to disinfect surfaces habitually.

The kitchen sink has more germs than a toilet seat, says Dr Charles Gerba.Credit:Belinda Pratten

The only thing bleach will do is get rid of the nasty black spot on the rubber ring which won't cause any illnesses

"Ideas about sterilising and disinfecting household surfaces are just nonsensical," she says. "We're not performing surgery in our homes; nor do we have immunocompromised patients."

She urges people not to use bleach and other harsh chemicals, which can build up in the environment and enter our water supply.

'Touch Generation' ... Dr Charles Gerba says we are sharing more surfaces than people ever have in history.Credit:Virginia Star

"Practise good hygiene. All you need is soap and water or an alcohol-based sanitiser," she says.

Professor McLaws adds that faecal bacteria are not pathogenic and says it is enough to clean with an alcohol-based spray and to regularly wash chopping boards.

"We don't like bacteria because they spoil the food," she explains. "But you need pathogenic bacteria to make us sick immediately."

Dr Gerba describes us as the 'Touch Generation' and says there is an urgent need to develop better cleaning habits.

"The elevator button for the ground floor, the handle of your shopping trolley, the television remote in your hands. We're touching and sharing more surfaces every day than people ever have in history," he says.

And to those locked in the debate about whether some exposure to dirt can help boost the immune system, Dr Gerba cautions not to confuse dirt with germs.

"You can have the cleanest looking house but have bad germs that can cause illness," he says. "A child under two will put their finger in their face about 80 times an hour and every time there is the potential of moving germs into his face."

He says regular disinfections reduced the risks of getting an illness from germs and kept the odds in our favour.

Dr Gerba also says that the water left in the base of the drum of a washing machine harboured germs. His solution is to give it a weekly "mouth wash" by using a bleach tablet.

"Nowadays people prefer to do cold water washes on short cycles," he says. "But you reduce the number of germs by using warm cycles."

But Professor McLaws insists that normal detergent is sufficient to kill most pathogens that can cause illnesses.

"We don't eat or lick our clothes," she says. "The only thing bleach will do is get rid of the nasty black spot on the rubber ring, which won't cause any illnesses."